title: A tale of two repressors.
abstract: Few proteins have had such a strong impact on a field, as the lac repressor and λ repressor have had in Molecular Biology in bacteria. The genes required for lactose utilization are negatively regulated; the lac repressor binds to an upstream operator blocking the transcription of the enzymes necessary for lactose utilization. A similar switch regulates the virus life cycle; λ repressor binds to an operator site and blocks transcription of the phage genes necessary for lytic development. It is now 50 years since Jacob and Monod first proposed a model for gene regulation, which survives essentially unchanged in contemporary textbooks. Jacob, F. & Monod, J. (1961). Genetic regulatory mechanisms in the synthesis of proteins. J. Mol. Biol. 3, 318-356. This model provides a cogent depiction of how a set of genes can be coordinately transcribed in response to environmental conditions and regulates metabolic events in the cell. A historical perspective that illustrates the role these two repressor molecules played and their contribution to our understanding of gene regulation is presented.
authors.affiliation: Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. lewis@mail.med.upenn.edu
authors.forename: Mitchell
authors.initials: M
authors.lastname: Lewis
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics*; D004269:DNA, Bacterial / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D015967:Gene Expression Regulation, Viral; D049673:History, 20th Century; D049674:History, 21st Century; D056968:Lac Repressors / Q000378:metabolism*; D008967:Molecular Biology / Q000266:history* / Q000639:trends; D009875:Operator Regions, Genetic; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004279:DNA, Viral; D029968:Escherichia coli Proteins; D056968:Lac Repressors; C539064:LacI protein, E coli; D012097:Repressor Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins